The subject matter described and/or illustrated herein relates generally to electrical switches, and more particularly, to solenoids for electrical switches.
Electrical switches (e.g., contactors, relays, and the like) exist today for opening and closing an electrical circuit between various electrical devices. For example, electrical switches are sometimes used to electrically connect and disconnect an electrical device from an electrical power source. Typical electrical switches include an actuator and one or more movable contacts connected to the actuator. Electrical current is applied to the actuator to move the movable contact into or out of engagement with stationary contacts that are electrically connected to corresponding ones of the electrical devices. The electrical circuit between the electrical devices is thereby completed or broken depending on whether the movable contact is engaged or disengaged with the stationary contacts.
The actuator of some known electrical switches is a solenoid, which may include a coil that surrounds a movable core. A ferromagnetic coil shell typically extends around the coil. Energization of the coil with electrical power generates a magnetic flux that moves the movable core within the coil. The movable core is connected to an actuator rod that is connected to the movable contact of the electrical switch. As the movable core moves within the coil, the actuator rod and movable contact move along with the movable core to engage or disengage the movable contact from the stationary contacts.
The coil, coil shell, and/or other components of the solenoid and/or switch are selected to provide a predetermined amount of magnetic flux. The predetermined magnetic flux provides a predetermined movement force for moving the movable contact into or out of engagement with the stationary contacts. The movement force may need to be high enough to overcome the friction and/or inertia of the movable core and/or other components of the solenoid and/or switch, such as the actuator rod. The predetermined magnetic flux also provides a predetermined contact force for holding the movable contact in engagement with or disengagement from the stationary contacts. The movement force and/or the contact force may also need to be high enough to overcome the bias of a spring that biases the movable contact to be disengaged from or engaged with the stationary contacts. But, to provide even relatively small increases to the predetermined magnetic flux, a size of the coil, the coil shell, and/or other ferromagnetic components of the solenoid and/or the switch may need to be increased more than is desired. As the size of the coil, coil shell, and/or other ferromagnetic components increases, the solenoid and/or the switch may become undesirably bulky and/or heavy. Moreover, the increased amount of ferromagnetic material used to fabricate the coil, the coil shell, and/or the other ferromagnetic components may increase a cost of the solenoid and/or the switch. Further, at least some of the increased magnetic flux may be wasted because the physical coupling between the coil and the movable core may decrease as the size of the coil increases.